Presently, a touch screen with the advantages of easy and convenient operation and humanization is widely used in various kinds of electronic products such as a mobile phone, a PDA (personal digital assistant), a GPS (global position system), a PMP (MP3, MP4, etc.), a tablet personal computer and the like.
Conventionally, an induction unit in the touch screen is judged whether to be touched or not by detecting a self-capacitance thereof. Thus, it becomes more important to accurately detect the self-capacitance generated by the induction unit in the touch screen when the induction unit is touched.
However, a conventional method of detecting capacitance has the disadvantage of low detection accuracy. When detecting the capacitance generated by touching the induction unit, an error occurs because of the existence of mutual-capacitance, thereby decreasing detection accuracy. Therefore, it is difficult to correctly judge whether the induction unit is touched or not.